Direct URCA process in neutron stars

Lattimer, James M.; Pethick, C. J.; Prakash, Madappa; Haensel, P.

doi:10.1103/physrevlett.66.2701

Cited by 781 publications

(857 citation statements)

References 27 publications

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“…The direct Urca process in neutron stars, in which the degenerate nucleons beta decay leading to subsequent cooling due to the loss of neutrinos and antineutrinos, requires a minimum fraction of protons, x=1/9, in the low-temperature limit and in the absence of muons due to energy and momentum conservation (Lattimer et al 1991). Assuming again the quadratic approximation for the dependence of the energy on the neutron excess, this condition, from …”

Section: The Direct Urca Processmentioning

confidence: 99%

Symmetry Parameter Constraints from a Lower Bound on Neutron-matter Energy

Tews¹,

Lattimer²,

Ohnishi³

et al. 2017

ApJ

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290

213

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We propose the existence of a lower bound on the energy of pure neutron matter (PNM) on the basis of unitary-gas considerations. We discuss its justification from experimental studies of cold atoms as well as from theoretical studies of neutron matter. We demonstrate that this bound results in limits to the density-dependent symmetry energy, which is the difference between the energies of symmetric nuclear matter and PNM. In particular, this bound leads to a lower limit to the volume symmetry energy parameter S 0 . In addition, for assumed values of S 0 above this minimum, this bound implies both upper and lower limits to the symmetry energy slope parameter L, which describes the lowest-order density dependence of the symmetry energy. A lower bound on neutron-matter incompressibility is also obtained. These bounds are found to be consistent with both recent calculations of the energies of PNM and constraints from nuclear experiments. Our results are significant because several equations of state that are currently used in astrophysical simulations of supernovae and neutron star mergers, as well as in nuclear physics simulations of heavy-ion collisions, have symmetry energy parameters that violate these bounds. Furthermore, below the nuclear saturation density, the bound on neutron-matter energies leads to a lower limit to the density-dependent symmetry energy, which leads to upper limits to the nuclear surface symmetry parameter and the neutron-star crust-core boundary. We also obtain a lower limit to the neutron-skin thicknesses of neutronrich nuclei. Above the nuclear saturation density, the bound on neutron-matter energies also leads to an upper limit to the symmetry energy, with implications for neutron-star cooling via the direct Urca process.

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Section: The Direct Urca Processmentioning

confidence: 99%

Symmetry Parameter Constraints from a Lower Bound on Neutron-matter Energy

Tews¹,

Lattimer²,

Ohnishi³

et al. 2017

ApJ

Self Cite

290

213

View full text Add to dashboard Cite

show abstract

“…It was a paper by Lattimer et al (1991) that opened the wide discussion of the direct Urca process. It showed that for some realistic models of neutron star matter, x p exceeded x cp at densities several times the standard nuclear matter density ρ 0 .…”

Section: (B) Nucleon Direct Urca Thresholdmentioning

confidence: 99%

“…In this case one can obtain an approximate relationship (Lattimer et al 1991;Levenfish and Yakovlev 1994b)…”

Section: ) Agrees With the Factor R (D)mentioning

confidence: 99%

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Neutrino emission from neutron stars

Kaminker²,

et al. 2001

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We review the main neutrino emission mechanisms in neutron star crusts and cores. Among them are the well-known reactions such as the electron-positron annihilation, plasmon decay, neutrino bremsstrahlung of electrons colliding with atomic nuclei in the crust, as well as the Urca processes and neutrino bremsstrahlung in nucleon-nucleon collisions in the core. We emphasize recent theoretical achievements, for instance, band structure effects in neutrino emission due to scattering of electrons in Coulomb crystals of atomic nuclei. We consider the standard composition of matter (neutrons, protons, electrons, muons, hyperons) in the core, and also the case of exotic constituents such as the pion or kaon condensates and quark matter. We discuss the reduction of the neutrino emissivities by nucleon superfluidity, as well as the specific neutrino emission produced by Cooper pairing of the superfluid particles. We also analyze the effects of strong magnetic fields on some reactions, such as the direct Urca process and the neutrino synchrotron emission of electrons. The results are presented in the form convenient for practical use. We illustrate the effects of various neutrino reactions on the cooling of neutron stars. In particular, the neutrino emission in the crust is critical in setting the initial thermal relaxation between the core and the crust. Finally, we discuss the prospects of exploring the properties of supernuclear matter by confronting cooling simulations with observations of the thermal radiation from isolated neutron stars.

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“…The interaction crosssection for electron neutrino and muon neutrinos with the substance is very small and is approximately 10 -44 cm 2 for neutrinos with energies 1 MeV. The full rate neutrino scattering on electrons, protons or neutrons is given by the formula [20] ܲ ఔ ൎ 9. 6.9 Numerical evaluation of neutrino luminosity in magnetosphere of collapsing star.…”

Section: Neutrino Absorption In Magnetospherementioning

confidence: 99%

Generation of high-energy particles, neutrino and fotons in magnetosphere of collapsing star

Kryvdyk

2014

EPJ Web of Conferences

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Abstract. The generation of particles, photons and neutrinos in magnetosphere of collapsing star are considered. These processes are caused the self-interaction initial accelerating in magnetosphere protons and electrons. The second particles and photons will arise as a result of this self-interaction, which in turn will generate charged particles, photons and neutrino (cascade process). These processes are especially effective for the formation collapsing star magnetosphere from the secondary charged particles. In addition, the particles, photons and neutrinos will be generated in magnetosphere of collapsing star as result of these processes.

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Direct URCA process in neutron stars

Abstract: %e show that the direct URCA process can occur in neutron stars if the proton concentration exceeds some critical value in the range (11 -15)%. The proton concentration, which is determined by the poorly

Cited by 781 publications

References 27 publications

Symmetry Parameter Constraints from a Lower Bound on Neutron-matter Energy

Symmetry Parameter Constraints from a Lower Bound on Neutron-matter Energy

Neutrino emission from neutron stars

Generation of high-energy particles, neutrino and fotons in magnetosphere of collapsing star

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